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An analysis of the molecular origin of osmolyte-dependent protein stability

Authors

  • Jörg Rösgen,

    Corresponding author
    1. Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston, Texas 77555-1052, USA
    • Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, 5.154 Medical Research Building, Galveston, Texas, 77555-1052, USA; fax: (409) 747-4751.
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  • B. Montgomery Pettitt,

    1. Department of Chemistry, University of Houston, Houston, Texas 77204-5003, USA
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  • David Wayne Bolen

    1. Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston, Texas 77555-1052, USA
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Abstract

Protein solvation is the key determinant for isothermal, concentration-dependent effects on protein equilibria, such as folding. The required solvation information can be extracted from experimental thermodynamic data using Kirkwood-Buff theory. Here we derive and discuss general properties of proteins and osmolytes that are pertinent to their biochemical behavior. We find that hydration depends very little on osmolyte concentration and type. Strong dependencies on both osmolyte concentration and type are found for osmolyte self-solvation and protein–osmolyte solvation changes upon unfolding. However, solvation in osmolyte solutions does not involve complex concentration dependencies as found in organic molecules that are not used as osmolytes in nature. It is argued that the simple solvation behavior of naturally occurring osmolytes is a prerequisite for their usefulness in osmotic regulation in vivo.

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